Wait for it... Awaclus is going to post a FTFY that crosses out your entire guess other than the 6P. And he may add 3-5 for good measure.
Anyway, here's the thing: most people characterize games with attacks as "brutal" because the attacks can be so effective, particularly in multi-player and particularly junkers since the curse and ruins piles are +10 per extra player. But some junkers aren't so bad. Torturer gives the curse to hand so players can take the curse if they have a trasher in hand, and once curses run out, they do nothing, and they also guarantee the kingdom has a big draw card. Mountebank is worse. Also Cultist.
But even a game with both curses and ruins, if the junkers are good ones, isn't going to last long even in multi-player, because that's two piles down. It may even end up being an Estate rush and end pretty quickly. Players in my IRL playgroup often insist on trying to build to Provinces even in a slog kingdom, and that can be an easy win on piles.
There aren't many great trashing attacks, though again in multiplayer they can be bad, but most of them have cost ranges and can be bought around if necessary. Discard attacks work nicely, but do nothing in multiples.
The Magpie/Scrying Pool suggestion is pretty darn good. Cards with fiddly mechanics or lots of decision-making can be worse than attacks in terms of slowing down games. I'll add a few:
Plenty of actions, Oracle as the only draw.
Wolf Den + Swindler + Ruins + lots of $3/$4 cards and a Trash-one. Good luck remembering what you have only one copy of. Or what you've given opponents only one copy of.
Mountebank + Wall + no trashing.
And what's the worst attack to be on the receiving end of?
Other than a pin like one of the Masquerade pins or the rare Bureaucrat pin, how about one of the various Possession pins? Possession + Haunted Woods allows your opponent to just give you a junk hand every turn.
KC/Village/Torturer is starting to sound pretty good, isn't it? Heck, that's probably even a nice engine board that's fun to play.
Looks like you're new. What you'll discover with further reading and experience is that Dominion is a far more complex and interesting game than you ever imagined, and that games can get both a lot worse and a lot better than you've even seen yet. You haven't seen bad until you've won a game with a negative score, or seen good until you've piledrived (piledriven?) all the Provinces or Colonies in one turn.